In modern ordnance there is a strong requirement for explosives having both good thermal stability, impact insensitivity and explosive performance. However, these requirements are somewhat mutually exclusive. Those explosives having good thermal stability and impact insensitivity exhibit poorer explosive performances and vice versa. This energetic material, crystalline 2,4-dinitroimidazole, (Crystalline DNI-24) we have discovered has both good thermal stability and impact insensitivity, as will be described and documented hereinafter. The explosive of the prior art are generally less attractive and, unwanted because of many unintentional initiations of munitions by either impact or shock aboard cargo ships, aircraft carriers, ammunition trains and nuclear warheads. Triaminotrinitrobenzene (TATB) is currently employed for insensitive high explosive applications in nuclear weapons, but this explosive does not provide sufficiently high energetic performance in order to replace RDX and HMX in some applications. Therefore, there is a continuing need for explosives which are powerful, yet resistant to accidental and sympathetic initiation.
The compound 2,4-dinitroimidazole (DNI-24) is known in the literature. Although these imidazole derivatives were studied exclusively for their pharamacological medicinal chemistry, the nitro derivatives of this heterocyclic system were not studied for their use in explosives and propellants applications. There is nothing in the literature, however, which in any way suggests either any explosive or propellant properties or the thermal stability and impact insensitivity of 2,4-dinitroimidazole (DNI-24) and its isomer 1,4-dinitroimidazole (DNI-14). As a part of a program to develop more powerful explosives and propellants, we have discovered that the crystalline DNI-24 is energetic for propellant and explosives applications based on experimental results.
The starting point for the synthesis of these two targeted compounds is Imidazole and this is commercially available from Fluka Chemical Company, Ronkonkoma, N.Y. This can be nitrated to give the 4-nitroimidazole wish in good yield. The nitro group on 4-nitroimidazole becomes the initiating point for introducing further nitro groups.